Reconstitution of Daptomycin for Injection Vial

Daptomycin for Injection is supplied in single-dose vials, each containing 350 mg daptomycin as a sterile, lyophilized powder. The contents of a Daptomycin for Injection vial should be reconstituted, using aseptic technique, to 50 mg per mL as follows:

1. To minimize foaming, AVOID vigorous agitation or shaking of the vial during or after reconstitution.
2. Remove the polypropylene flip-off cap from the Daptomycin for Injection vial to expose the central portion of the rubber stopper.
3. Wipe the top of the rubber stopper with an alcohol swab or other antiseptic solution and allow to dry. After cleaning, do not touch the rubber stopper or allow it to touch any other surface.
4. Slowly transfer 7 mL of 0.9% sodium chloride injection through the center of the rubber stopper into the Daptomycin for Injection vial, pointing the transfer needle toward the wall of the vial. It is recommended that a beveled sterile transfer needle that is 21 gauge or smaller in diameter, or a needleless device is used, pointing the transfer needle toward the wall of the vial.
5. Ensure that all of the daptomycin for injection powder is wetted by gently rotating the vial.
   1. Allow the wetted product to stand undisturbed for 10 minutes.
   2. Gently rotate or swirl the vial contents for a few minutes, as needed, to obtain a completely reconstituted solution.

Administration Instructions

Parenteral drug products should be inspected visually for particulate matter prior to administration.

Slowly remove reconstituted liquid (50 mg daptomycin per mL) from the vial using a beveled sterile needle that is 21 gauge or smaller in diameter. Administer as an intravenous injection or infusion as described below:

Adults

Intravenous Injection over a period of 2 minutes

• For intravenous (IV) injection over a period of 2 minutes in adult patients only: Administer the appropriate volume of the reconstituted Daptomycin for Injection (concentration of 50 mg per mL).

Intravenous Infusion over a period of 30 minutes

• For intravenous (IV) infusion over a period of 30 minutes in adult patients: The appropriate volume of the reconstituted Daptomycin for Injection (concentration of 50 mg per mL) should be further diluted, using aseptic technique, into a 50 mL IV infusion bag containing 0.9% sodium chloride injection.

Pediatric Patients (1 to 17 Years of Age)

Intravenous Infusion over a period of 30 or 60 minutes

• Unlike in Adults, do NOT administer Daptomycin for Injection by injection over a two (2) minute period to pediatric patients [see Dosage and Administration ( 2.1)].
• For Intravenous infusion over a period of 60 minutes in pediatric patients 1 to 6 years of age:The appropriate volume of the reconstituted Daptomycin for Injection (concentration of 50 mg per mL) should be further diluted, using aseptic technique, into an intravenous infusion bag containing 25 mL of 0.9% sodium chloride injection. The infusion rate should be maintained at 0.42 mL/minute over the 60-minute period.
• For Intravenous infusion over a period of 30 minutes in pediatric patients 7 to 17 years of age: The appropriate volume of the reconstituted Daptomycin for Injection (concentration of 50 mg per mL) should be further diluted, using aseptic technique, into a 50 mL IV infusion bag containing 0.9% sodium chloride injection. The infusion rate should be maintained at 1.67 mL/minute over the 30minute period.

No preservative or bacteriostatic agent is present in this product. Aseptic technique must be used in the preparation of final IV solution. Do not exceed the In-Use storage conditions of the reconstituted and diluted solutions of Daptomycin for Injection described below. Discard unused portions of daptomycin for injection.

In-Use Storage Conditions for Daptomycin for Injection Once Reconstituted in Acceptable Intravenous Diluents

Stability studies have shown that the reconstituted solution is stable in the vial for 12 hours at room temperature and up to 48 hours if stored under refrigeration between 2° and 8°C (36° and 46°F).

The diluted solution is stable in the infusion bag for 12 hours at room temperature and 48 hours if stored under refrigeration. The combined storage time (reconstituted solution in vial and diluted solution in infusion bag) should not exceed 12 hours at room temperature or 48 hours under refrigeration.

Clinical Trial Experience in Adult Patients

Clinical trials enrolled 1,864 adult patients treated with daptomycin and 1,416 treated with comparator.

Complicated Skin and Skin Structure Infection Trials in Adults

In Phase 3 complicated skin and skin structure infection (cSSSI) trials in adult patients, daptomycin was discontinued in 15/534 (2.8%) patients due to an adverse reaction, while comparator was discontinued in 17/558 (3.0%) patients.

The rates of the most common adverse reactions, organized by body system, observed in adult patients with cSSSI (receiving 4 mg/kg daptomycin) are displayed in Table 6.

Drug-related adverse reactions (possibly or probably drug-related) that occurred in <1% of adult patients receiving daptomycin in the cSSSI trials are as follows:

Body as a Whole: fatigue, weakness, rigors, flushing, hypersensitivity

Blood/Lymphatic System: leukocytosis, thrombocytopenia, thrombocytosis, eosinophilia, increased International Normalized Ratio (INR)

Cardiovascular System: supraventricular arrhythmia

Dermatologic System: eczema

Digestive System: abdominal distension, stomatitis, jaundice, increased serum lactate dehydrogenase

Metabolic/Nutritional System: hypomagnesemia, increased serum bicarbonate, electrolyte disturbance

Musculoskeletal System: myalgia, muscle cramps, muscle weakness, arthralgia

Nervous System: vertigo, mental status change, paresthesia

Special Senses: taste disturbance, eye irritation

S. aureus Bacteremia/Endocarditis Trial in Adults

In the S. aureus bacteremia/endocarditis trial involving adult patients, daptomycin was discontinued in 20/120 (16.7%) patients due to an adverse reaction, while comparator was discontinued in 21/116 (18.1%) patients.

Serious Gram-negative infections (including bloodstream infections) were reported in 10/120 (8.3%) daptomycin-treated patients and 0/115 comparator-treated patients. Comparator-treated patients received dual therapy that included initial gentamicin for 4 days. Infections were reported during treatment and during early and late follow-up. Gram-negative infections included cholangitis, alcoholic pancreatitis, sternal osteomyelitis/mediastinitis, bowel infarction, recurrent Crohn's disease, recurrent line sepsis, and recurrent urosepsis caused by a number of different Gram-negative bacteria.

The rates of the most common adverse reactions, organized by System Organ Class (SOC), observed in adult patients with S. aureus bacteremia/endocarditis (receiving 6 mg/kg daptomycin) are displayed in Table 7.

The following reactions, not included above, were reported as possibly or probably drug-related in the daptomycin-treated group:

Blood and Lymphatic System Disorders: eosinophilia, lymphadenopathy, thrombocythemia, thrombocytopenia

Cardiac Disorders: atrial fibrillation, atrial flutter, cardiac arrest

Ear and Labyrinth Disorders: tinnitus

Eye Disorders: vision blurred

Gastrointestinal Disorders: dry mouth, epigastric discomfort, gingival pain, hypoesthesia oral

Infections and Infestations: candidal infection NOS, vaginal candidiasis, fungemia, oral candidiasis, urinary tract infection fungal

Investigations: blood phosphorous increased, blood alkaline phosphatase increased, INR increased, liver function test abnormal, alanine aminotransferase increased, aspartate aminotransferase increased, prothrombin time prolonged

Metabolism and Nutrition Disorders: appetite decreased NOS

Musculoskeletal and Connective Tissue Disorders: myalgia

Nervous System Disorders: dyskinesia, paresthesia

Psychiatric Disorders: hallucination NOS

Renal and Urinary Disorders: proteinuria, renal impairment NOS

Skin and Subcutaneous Tissue Disorders: pruritus generalized, rash vesicular

Other Trials in Adults

In Phase 3 trials of community-acquired pneumonia (CAP) in adult patients, the death rate and rates of serious cardiorespiratory adverse events were higher in daptomycin-treated patients than in comparator-treated patients. These differences were due to lack of therapeutic effectiveness of daptomycin in the treatment of CAP in patients experiencing these adverse events [see Indications and Usage ( 1.4)] .

Laboratory Changes in Adults

Complicated Skin and Skin Structure Infection Trials in Adults

In Phase 3 cSSSI trials of adult patients receiving daptomycin at a dose of 4 mg/kg, elevations in CPK were reported as clinical adverse events in 15/534 (2.8%) daptomycin-treated patients, compared with 10/558 (1.8%) comparator-treated patients. Of the 534 patients treated with daptomycin, 1 (0.2%) had symptoms of muscle pain or weakness associated with CPK elevations to greater than 4 times the upper limit of normal (ULN). The symptoms resolved within 3 days and CPK returned to normal within 7 to 10 days after treatment was discontinued [see Warnings and Precautions ( 5.2)] . Table 8 summarizes the CPK shifts from Baseline through End of Therapy in the cSSSI adult trials.

S. aureus Bacteremia/Endocarditis Trial in Adults

In the S. aureus bacteremia/endocarditis trial in adult patients, at a dose of 6 mg/kg, 11/120 (9.2%) daptomycin-treated patients, including two patients with baseline CPK levels >500 U/L, had CPK elevations to levels >500 U/L, compared with 1/116 (0.9%) comparator-treated patients. Of the 11 daptomycin-treated patients, 4 had prior or concomitant treatment with an HMG-CoA reductase inhibitor. Three of these 11 daptomycin-treated patients discontinued therapy due to CPK elevation, while the one comparator-treated patient did not discontinue therapy [see Warnings and Precautions ( 5.2)] .

Clinical Trial Experience in Pediatric Patients

Complicated Skin and Skin Structure Infection Trial in Pediatric Patients

The safety of daptomycin was evaluated in one clinical trial (in cSSSI), which included 256 pediatric patients (1 to 17 years of age) treated with intravenous daptomycin and 133 patients treated with comparator agents. Patients were given age-dependent doses once daily for a treatment period of up to 14 days (median treatment period was 3 days). The doses given by age group were as follows: 10 mg/kg for 1 to ‹ 2 years, 9 mg/kg for 2 to 6 years, 7 mg/kg for 7 to 11 years and 5 mg/kg for 12 to 17 years of age [see Clinical Studies ( 14)] . Patients treated with daptomycin were (51%) male, (49%) female and (46%) Caucasian and (32%) Asian.

Adverse Reactions Leading to Discontinuation

In the cSSSI study, daptomycin was discontinued in 7/256 (2.7%) patients due to an adverse reaction, while comparator was discontinued in 7/133 (5.3%) patients.

Most Common Adverse Reactions

The rates of the most common adverse reactions, organized by body system, observed in these pediatric patients with cSSSI are displayed in Table 9.

The safety profile in the clinical trial of cSSSI pediatric patients was similar to that observed in the cSSSI adult patients.

S. aureus Bacteremia Trial in Pediatric Patients

The safety of daptomycin was evaluated in one clinical trial (in S. aureus bacteremia), which treated 55 pediatric patients with intravenous daptomycin and 26 patients with comparator agents. Patients were given age-dependent doses once daily for a treatment period of up to 42 days (mean duration of IV treatment was 12 days). The doses by age group were as follows: 12 mg/kg for 1 to <6 years, 9 mg/kg for 7 to 11 years and 7 mg/kg for 12 to 17 years of age [see Clinical Studies ( 14)] . Patients treated with daptomycin were (69%) male and (31%) female. No patients 1 to <2 years of age were enrolled.

Adverse Reactions Leading to Discontinuation

In the bacteremia study, daptomycin was discontinued in 3/55 (5.5%) patients due to an adverse reaction, while comparator was discontinued in 2/26 (7.7%) patients.

Most Common Adverse Reactions

The rates of the most common adverse reactions, organized by body system, observed in these pediatric patients with bacteremia are displayed in Table 10.

Risk Summary

Limited published data on use of daptomycin in pregnant women are insufficient to inform a drug-associated risk for major birth defects and miscarriage. In animal reproduction studies performed in rats and rabbits daptomycin was administered intravenously during organogenesis at doses 2 and 4-times, respectively, the recommended 6 mg/kg human dose (on a body surface area basis). No evidence of adverse developmental outcomes was observed.

The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data

In pregnant rats, daptomycin was administered intravenously at doses of 5, 20, or 75 mg/kg/day during the gestation days 6 to 18. Maternal body weight gain was decreased at 75 mg/kg/day.

No embryo/fetal effects were noted at the highest dose of 75 mg/kg/day, a dose approximately 2-fold higher than in humans at the recommended maximum dose of 6 mg/kg (based on body surface area).

In pregnant rabbits, daptomycin was administered intravenously at doses of 5, 20, or 75 mg/kg/day during the gestation days 6 to 15. Maternal body weight gain and food consumption were decreased at 75 mg/kg/day. No embryo/fetal effects were noted at the highest dose of 75 mg/kg/day, a dose approximately 4-fold higher than in humans at the maximum recommended dose of 6 mg/kg (based on body surface area).

In a combined fertility and pre/postnatal development study, daptomycin was administered intravenously to female rats at doses of 2, 25, 75 mg/kg/day from 14-days pre-mating through lactation/postpartum day 20). No effects on pre/postnatal development were observed up to the highest dose of 75 mg/kg/day, a dose approximately 2-fold higher than the maximum recommended human dose of 6 mg/kg (based on body surface area) 1.

Risk Summary

Limited published data report that daptomycin is present in human milk at infant doses of 0.1% of the maternal dose (see Data) 2,3,4. There is no information on the effects of daptomycin on the breastfed infant or the effects of daptomycin on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for daptomycin and any potential adverse effects on the breastfed infant from daptomycin or from the underlying maternal condition.

Daptomycin Administered over a 30-Minute Period in Adults

The mean and standard deviation (SD) pharmacokinetic parameters of daptomycin at steady-state following intravenous (IV) administration of daptomycin over a 30-minute period at 4 to 12 mg/kg every 24h to healthy young adults are summarized in Table 11.

Daptomycin pharmacokinetics were generally linear and time-independent at daptomycin doses of 4 to 12 mg/kg every 24h administered by IV infusion over a 30-minute period for up to 14 days. Steady-state trough concentrations were achieved by the third daily dose. The mean (SD) steady-state trough concentrations attained following the administration of 4, 6, 8, 10, and 12 mg/kg every 24h were 5.9 (1.6), 6.7 (1.6), 10.3 (5.5), 12.9 (2.9), and 13.7 (5.2) mcg/mL, respectively.

Daptomycin Administered over a 2-Minute Period in Adults

Following IV administration of daptomycin over a 2-minute period to healthy adult volunteers at doses of 4 mg/kg (N=8) and 6 mg/kg (N=12), the mean (SD) steady-state systemic exposure (AUC) values were 475 (71) and 701 (82) mcg•h/mL, respectively. Values for maximum plasma concentration (C max) at the end of the 2-minute period could not be determined adequately in this study. However, using pharmacokinetic parameters from 14 healthy adult volunteers who received a single dose of daptomycin 6 mg/kg IV administered over a 30-minute period in a separate study, steady-state C max values were simulated for daptomycin 4 and 6 mg/kg IV administered over a 2-minute period. The simulated mean (SD) steady-state C max values were 77.7 (8.1) and 116.6 (12.2) mcg/mL, respectively.

Distribution

Daptomycin is reversibly bound to human plasma proteins, primarily to serum albumin, in a concentration-independent manner. The overall mean binding ranges from 90 to 93%.

In clinical studies, mean serum protein binding in adult subjects with creatinine clearance (CL CR) ≥30 mL/min was comparable to that observed in healthy adult subjects with normal renal function.

However, there was a trend toward decreasing serum protein binding among subjects with CL CR <30 mL/min (88%), including those receiving hemodialysis (86%) and continuous ambulatory peritoneal dialysis (CAPD) (84%). The protein binding of daptomycin in adult subjects with moderate hepatic impairment (Child-Pugh Class B) was similar to that in healthy adult subjects.

The volume of distribution at steady-state (V ss) of daptomycin in healthy adult subjects was approximately 0.1 L/kg and was independent of dose.

Metabolism

In in vitro studies, daptomycin was not metabolized by human liver microsomes.

In 5 healthy adults after infusion of radiolabeled 14C-daptomycin, the plasma total radioactivity was similar to the concentration determined by microbiological assay. Inactive metabolites were detected in urine, as determined by the difference between total radioactive concentrations and microbiologically active concentrations. In a separate study, no metabolites were observed in plasma on Day 1 following the administration of daptomycin at 6 mg/kg to adult subjects. Minor amounts of three oxidative metabolites and one unidentified compound were detected in urine. The site of metabolism has not been identified.

Excretion

Daptomycin is excreted primarily by the kidneys. In a mass balance study of 5 healthy adult subjects using radiolabeled daptomycin, approximately 78% of the administered dose was recovered from urine based on total radioactivity (approximately 52% of the dose based on microbiologically active concentrations), and 5.7% of the administered dose was recovered from feces (collected for up to 9 days) based on total radioactivity.

Specific Populations

Patients with Renal Impairment

Population-derived pharmacokinetic parameters were determined for infected adult patients (complicated skin and skin structure infections [cSSSI] and S. aureus bacteremia) and noninfected adult subjects with various degrees of renal function ( Table 12). Total plasma clearance (CL T), elimination half-life (t 1/2), and volume of distribution at steady-state (V ss) in patients with cSSSI were similar to those in patients with S. aureus bacteremia. Following administration of daptomycin 4 mg/kg every 24h by IV infusion over a 30-minute period, the mean CL T was 9%, 22%, and 46% lower among subjects and patients with mild (CL CR 50 to 80 mL/min), moderate (CL CR 30 to <50 mL/min), and severe (CL CR <30 mL/min) renal impairment, respectively, than in those with normal renal function (CL CR >80 mL/min).

The mean steady-state systemic exposure (AUC), t 1/2, and V ss increased with decreasing renal function, although the mean AUC for patients with CL CR 30 to 80 mL/min was not markedly different from the mean AUC for patients with normal renal function. The mean AUC for patients with CL CR <30 mL/min and for patients on dialysis (CAPD and hemodialysis dosed post-dialysis) was approximately 2 and 3 times higher, respectively, than for patients with normal renal function. The mean C max ranged from 60 to 70 mcg/mL in patients with CL CR ≥30 mL/min, while the mean C max for patients with CL CR <30 mL/min ranged from 41 to 58 mcg/mL. After administration of daptomycin 6 mg/kg every 24h by IV infusion over a 30-minute period, the mean C max ranged from 80 to 114 mcg/mL in patients with mild to moderate renal impairment and was similar to that of patients with normal renal function.

Because renal excretion is the primary route of elimination, adjustment of daptomycin dosage interval is necessary in adult patients with severe renal impairment (CL CR <30 mL/min) [see Dosage and Administration ( 2.6)] .

Patients with Hepatic Impairment

The pharmacokinetics of daptomycin were evaluated in 10 adult subjects with moderate hepatic impairment (Child-Pugh Class B) and compared with those in healthy adult volunteers (N=9) matched for gender, age, and weight. The pharmacokinetics of daptomycin were not altered in subjects with moderate hepatic impairment. No dosage adjustment is warranted when daptomycin is administered to patients with mild to moderate hepatic impairment. The pharmacokinetics of daptomycin in patients with severe hepatic impairment (Child-Pugh Class C) have not been evaluated.

Gender

No clinically significant gender-related differences in daptomycin pharmacokinetics have been observed. No dosage adjustment is warranted based on gender when daptomycin is administered.

Geriatric Patients

The pharmacokinetics of daptomycin were evaluated in 12 healthy elderly subjects (≥75 years of age) and 11 healthy young adult controls (18 to 30 years of age). Following administration of a single 4 mg/kg dose of daptomycin by IV infusion over a 30-minute period, the mean total clearance of daptomycin was approximately 35% lower and the mean AUC 0-∞ was approximately 58% higher in elderly subjects than in healthy young adult subjects. There were no differences in C max[see Use in Specific Populations ( 8.5)] .

Obese Patients

The pharmacokinetics of daptomycin were evaluated in 6 moderately obese (Body Mass Index [BMI] 25 to 39.9 kg/m 2) and 6 extremely obese (BMI ≥40 kg/m 2) adult subjects and controls matched for age, gender, and renal function. Following administration of daptomycin by IV infusion over a 30-minute period as a single 4 mg/kg dose based on total body weight, the total plasma clearance of daptomycin normalized to total body weight was approximately 15% lower in moderately obese subjects and 23% lower in extremely obese subjects than in nonobese controls. The AUC 0-∞ of daptomycin was approximately 30% higher in moderately obese subjects and 31% higher in extremely obese subjects than in nonobese controls. The differences were most likely due to differences in the renal clearance of daptomycin. No adjustment of daptomycin dosage is warranted in obese patients.

Pediatric Patients

The pharmacokinetics of daptomycin in pediatric subjects was evaluated in 3 single-dose pharmacokinetic studies. In general, body weight-normalized total body clearance in pediatric patients was higher than in adults and increased with a decrease of age, whereas elimination half-life tends to decrease with a decrease of age. Body weight-normalized total body clearance and elimination half-life of daptomycin in children 2 to 6 years of age were similar at different doses.

A study was conducted to assess safety, efficacy, and pharmacokinetics of daptomycin in pediatric patients (1 to 17 years old, inclusive) with cSSSI caused by Gram-positive pathogens. Patients were enrolled into 4 age groups [see Clinical Studies ( 14.1)] , and intravenous daptomycin doses of 5 to 10 mg/kg once daily were administered. Following administration of multiple doses, daptomycin exposure (AUCss and Cmax,ss) was similar across different age groups after dose adjustment based on body weight and age (Table 13).

A study was conducted to assess safety, efficacy, and pharmacokinetics of daptomycin in pediatric patients with S. aureus bacteremia. Patients were enrolled into 3 age groups [see Clinical Studies ( 14.2)] , and intravenous doses of 7 to 12 mg/kg once daily were administered. Following administration of multiple doses, daptomycin exposure (AUC ss and C max,ss) was similar across different age groups after dose adjustment based on body weight and age (Table 14).

No patients 1 to <2 years of age were enrolled in the study. Simulation using a population pharmacokinetic model demonstrated that the AUCss of daptomycin in pediatric patients 1 to <22 years of age receiving 12 mg/kg once daily would be comparable to that in adult patients receiving 6 mg/kg once daily.

Drug-Drug Interactions

In Vitro Studies

In vitro studies with human hepatocytes indicate that daptomycin does not inhibit or induce the activities of the following human cytochrome P450 isoforms: 1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4. It is unlikely that daptomycin will inhibit or induce the metabolism of drugs metabolized by the P450 system.

Aztreonam

In a study in which 15 healthy adult subjects received a single dose of daptomycin 6 mg/kg IV and a combination dose of daptomycin 6 mg/kg IV and aztreonam 1 g IV, administered over a 30-minute period, the C max and AUC 0-∞ of daptomycin were not significantly altered by aztreonam.

Tobramycin

In a study in which 6 healthy adult males received a single dose of daptomycin 2 mg/kg IV, tobramycin 1 mg/kg IV, and both in combination, administered over a 30-minute period, the mean C max and AUC 0-∞ of daptomycin were 12.7% and 8.7% higher, respectively, when daptomycin was coadministered with tobramycin. The mean C max and AUC 0-∞ of tobramycin were 10.7% and 6.6% lower, respectively, when tobramycin was coadministered with daptomycin. These differences were not statistically significant. The interaction between daptomycin and tobramycin with a clinical dose of daptomycin is unknown.

Warfarin

In 16 healthy adult subjects, administration of daptomycin 6 mg/kg every 24h by IV infusion over a 30-minute period for 5 days, with coadministration of a single oral dose of warfarin (25 mg) on the 5th day, had no significant effect on the pharmacokinetics of either drug and did not significantly alter the INR (International Normalized Ratio).

Simvastatin

In 20 healthy adult subjects on a stable daily dose of simvastatin 40 mg, administration of daptomycin 4 mg/kg every 24h by IV infusion over a 30-minute period for 14 days (N=10) had no effect on plasma trough concentrations of simvastatin and was not associated with a higher incidence of adverse events, including skeletal myopathy, than in subjects receiving placebo once daily (N=10) [see Warnings and Precautions ( 5.2) and Drug Interactions ( 7.1)] .

Probenecid

Concomitant administration of probenecid (500 mg 4 times daily) and a single dose of daptomycin 4 mg/kg by IV infusion over a 30-minute period in adults did not significantly alter the C max or AUC 0-∞ of daptomycin.

Mechanism of Action

Daptomycin binds to bacterial cell membranes and causes a rapid depolarization of membrane potential. This loss of membrane potential causes inhibition of DNA, RNA, and protein synthesis, which results in bacterial cell death.

Resistance

The mechanism(s) of daptomycin resistance is not fully understood. Currently, there are no known transferable elements that confer resistance to daptomycin.

Interactions with Other Antibacterials

In vitro studies have investigated daptomycin interactions with other antibacterials. Antagonism, as determined by kill curve studies, has not been observed. In vitro synergistic interactions of daptomycin with aminoglycosides, β-lactam antibacterials, and rifampin have been shown against some isolates of staphylococci (including some methicillin-resistant isolates) and enterococci (including some vancomycin-resistant isolates).

Complicated Skin and Skin Structure Infection (cSSSI) Trials in Adults

The emergence of daptomycin non-susceptible isolates occurred in 2 infected patients across the set of Phase 2 and pivotal Phase 3 clinical trials of cSSSI in adult patients. In one case, a non-susceptible S. aureus was isolated from a patient in a Phase 2 trial who received daptomycin at less than the protocol-specified dose for the initial 5 days of therapy. In the second case, a non-susceptible Enterococcus faecalis was isolated from a patient with an infected chronic decubitus ulcer who was enrolled in a salvage trial.

S. aureus Bacteremia/Endocarditis and Other Post-Approval Trials in Adults

In subsequent clinical trials in adult patients, non-susceptible isolates were recovered. S. aureus was isolated from a patient in a compassionate-use trial and from 7 patients in the S. aureus bacteremia/endocarditis trial [see Clinical Studies ( 14.2)] . An E. faecium was isolated from a patient in a vancomycin-resistant enterococci trial.

Antimicrobial Activity

Daptomycin has been shown to be active against most isolates of the following microorganisms both in vitro and in clinical infections [see Indications and Usage ( 1)].

Gram-Positive Bacteria

Enterococcus faecalis (vancomycin-susceptible isolates only)

Staphylococcus aureus (including methicillin-resistant isolates)

Streptococcus agalactiae

Streptococcus dysgalactiae subsp. equisimilis

Streptococcus pyogenes

The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for daptomycin against isolates of genus or organism group. However, the efficacy of daptomycin in treating clinical infections due to these bacteria has not been established in adequate and well-controlled clinical trials.

Gram-Positive Bacteria

Corynebacterium jeikeium

Enterococcus faecalis (vancomycin-resistant isolates)

Enterococcus faecium (including vancomycin-resistant isolates)

Staphylococcus epidermidis (including methicillin-resistant isolates)

Staphylococcus haemolyticus

Susceptibility Testing

For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC

Adult Animals

In animals, daptomycin administration has been associated with effects on skeletal muscle. However, there were no changes in cardiac or smooth muscle. Skeletal muscle effects were characterized by microscopic degenerative/regenerative changes and variable elevations in creatine phosphokinase (CPK). No fibrosis or rhabdomyolysis was evident in repeat-dose studies up to the highest doses tested in rats (150 mg/kg/day) and dogs (100 mg/kg/day). The degree of skeletal myopathy showed no increase when treatment was extended from 1 month to up to 6 months. Severity was dose-dependent. All muscle effects, including microscopic changes, were fully reversible within 30 days following the cessation of dosing.

In adult animals, effects on peripheral nerve (characterized by axonal degeneration and frequently accompanied by significant losses of patellar reflex, gag reflex, and pain perception) were observed at daptomycin doses higher than those associated with skeletal myopathy. Deficits in the dogs' patellar reflexes were seen within 2 weeks after the start of treatment at 40 mg/kg/day (9 times the human C max at the 6 mg/kg/day dose), with some clinical improvement noted within 2 weeks after the cessation of dosing. However, at 75 mg/kg/day for 1 month, 7 of 8 dogs failed to regain full patellar reflex responses within a 3-month recovery period. In a separate study in dogs receiving doses of 75 and 100 mg/kg/day for 2 weeks, minimal residual histological changes were noted at 6 months after the cessation of dosing. However, recovery of peripheral nerve function was evident.

Tissue distribution studies in rats showed that daptomycin is retained in the kidney but appears to penetrate the blood-brain barrier only minimally following single and multiple doses.

Juvenile Animals

Target organs of daptomycin-related effects in 7-week-old juvenile dogs were skeletal muscle and nerve, the same target organs as in adult dogs. In juvenile dogs, nerve effects were noted at lower daptomycin blood concentrations than in adult dogs following 28 days of dosing. In contrast to adult dogs, juvenile dogs also showed evidence of effects in nerves of the spinal cord as well as peripheral nerves after 28 days of dosing. No nerve effects were noted in juvenile dogs following 14 days of dosing at doses up to 75 mg/kg/day.

Administration of daptomycin to 7-week-old juvenile dogs for 28 days at doses of 50 mg/kg/day produced minimal degenerative effects on the peripheral nerve and spinal cord in several animals, with no corresponding clinical signs. A dose of 150 mg/kg/day for 28 days produced minimal degeneration in the peripheral nerve and spinal cord as well as minimal to mild degeneration of the skeletal muscle in a majority of animals, accompanied by slight to severe muscle weakness evident in most dogs. Following a 28-day recovery phase, microscopic examination revealed recovery of the skeletal muscle and the ulnar nerve effects, but nerve degeneration in the sciatic nerve and spinal cord was still observed in all 150 mg/kg/day dogs.

Following once-daily administration of daptomycin to juvenile dogs for 28 days, microscopic effects in nerve tissue were noted at a C max value of 417 mcg/mL, which is approximately 3-fold less than the C max value associated with nerve effects in adult dogs treated once daily with daptomycin for 28 days (1308 mcg/mL).

Neonatal Animals

Neonatal dogs (4 to 31 days old) were more sensitive to daptomycin-related adverse nervous system and/or muscular system effects than either juvenile or adult dogs. In neonatal dogs, adverse nervous system and/or muscular system effects were associated with a C max value approximately 3-fold less than the C max in juvenile dogs, and 9-fold less than the C max in adult dogs following 28 days of dosing. At a dose of 25 mg/kg/day with associated C max and AUC inf values of 147 mcg/mL and 717 mcg•h/mL, respectively (1.6 and 1.0-fold the adult human C max and AUC, respectively, at the 6 mg/kg/day dose), mild clinical signs of twitching and one incidence of muscle rigidity were observed with no corresponding effect on body weight. These effects were found to be reversible within 28 days after treatment had stopped.

At higher dose levels of 50 and 75 mg/kg/day with associated C max and AUC inf values of ≥321 mcg/mL and ≥1470 mcg•h/mL, respectively, marked clinical signs of twitching, muscle rigidity in the limbs, and impaired use of limbs were observed. Resulting decreases in body weights and overall body condition at doses ≥50 mg/kg/day necessitated early discontinuation by postnatal day (PND)19.

Histopathological assessment did not reveal any daptomycin-related changes in the peripheral and central nervous system tissue, as well as in the skeletal muscle or other tissues assessed, at any dose level.

No adverse effects were observed in the dogs that received daptomycin at 10 mg/kg/day, the NOAEL, with associated C max and AUC inf values of 62 mcg/mL and 247 mcg•h/mL, respectively (or 0.6 and 0.4-fold the adult human C max and AUC, respectively at the 6 mg/kg dose).

Adults with S. aureus Bacteremia/Endocarditis

The efficacy of daptomycin in the treatment of adult patients with S. aureus bacteremia was demonstrated in a randomized, controlled, multinational, multicenter, open-label trial. In this trial, adult patients with at least one positive blood culture for S. aureus obtained within 2 calendar days prior to the first dose of study drug and irrespective of source were enrolled and randomized to either daptomycin (6 mg/kg IV every 24h) or standard of care [an anti-staphylococcal semi-synthetic penicillin 2 g IV every 24h (nafcillin, oxacillin, cloxacillin, or flucloxacillin) or vancomycin 1 g IV every 24h, each with initial gentamicin 1 mg/kg IV every 8 hours for first 4 days]. Of the patients in the comparator group, 93% received initial gentamicin for a median of 4 days, compared with 1 patient (<1%) in the daptomycin group. Patients with prosthetic heart valves, intravascular foreign material that was not planned for removal within 4 days after the first dose of study medication, severe neutropenia, known osteomyelitis, polymicrobial bloodstream infections, creatinine clearance <30 mL/min, and pneumonia were excluded.

Upon entry, patients were classified for likelihood of endocarditis using the modified Duke criteria (Possible, Definite, or Not Endocarditis). Echocardiography, including a transesophageal echocardiogram (TEE), was performed within 5 days following study enrollment. The choice of comparator agent was based on the oxacillin susceptibility of the S. aureus isolate. The duration of study treatment was based on the investigator's clinical diagnosis. Final diagnoses and outcome assessments at Test of Cure (6 weeks after the last treatment dose) were made by a treatment-blinded Adjudication Committee, using protocol-specified clinical definitions and a composite primary efficacy endpoint (clinical and microbiological success) at the Test of Cure visit.

A total of 246 patients ≥18 years of age (124 daptomycin, 122 comparator) with S. aureus bacteremia were randomized from 48 centers in the US and Europe. In the ITT population, 120 patients received daptomycin and 115 received comparator (62 received an anti-staphylococcal semi-synthetic penicillin and 53 received vancomycin). Thirty-five patients treated with an anti-staphylococcal semi-synthetic penicillin received vancomycin initially for 1 to 3 days, pending final susceptibility results for the S. aureus isolates. The median age among the 235 patients in the ITT population was 53 years (range: 21 to 91 years); 30/120 (25%) in the daptomycin group and 37/115 (32%) in the comparator group were ≥65 years of age. Of the 235 ITT patients, there were 141 (60%) males and 156 (66%) Caucasians across the two treatment groups. In addition, 176 (75%) of the ITT population had systemic inflammatory response syndrome (SIRS) at baseline and 85 (36%) had surgical procedures within 30 days prior to onset of the S. aureus bacteremia. Eighty-nine patients (38%) had bacteremia caused by methicillin-resistant S. aureus (MRSA). Entry diagnosis was based on the modified Duke criteria and comprised 37 (16%) Definite, 144 (61%) Possible, and 54 (23%) Not Endocarditis. Of the 37 patients with an entry diagnosis of Definite Endocarditis, all (100%) had a final diagnosis of infective endocarditis, and of the 144 patients with an entry diagnosis of Possible Endocarditis, 15 (10%) had a final diagnosis of infective endocarditis as assessed by the Adjudication Committee. Of the 54 patients with an entry diagnosis of Not Endocarditis, 1 (2%) had a final diagnosis of infective endocarditis as assessed by the Adjudication Committee.

In the ITT population, there were 182 patients with bacteremia and 53 patients with infective endocarditis as assessed by the Adjudication Committee, including 35 with right-sided endocarditis and 18 with left-sided endocarditis. The 182 patients with bacteremia comprised 121 with complicated S. aureus bacteremia and 61 with uncomplicated S. aureus bacteremia.

Complicated bacteremia was defined as S. aureus isolated from blood cultures obtained on at least 2 different calendar days, and/or metastatic foci of infection (deep tissue involvement), and classification of the patient as not having endocarditis according to the modified Duke criteria. Uncomplicated bacteremia was defined as S. aureus isolated from blood culture(s) obtained on a single calendar day, no metastatic foci of infection, no infection of prosthetic material, and classification of the patient as not having endocarditis according to the modified Duke criteria. The definition of right-sided infective endocarditis (RIE) used in the clinical trial was Definite or Possible Endocarditis according to the modified Duke criteria and no echocardiographic evidence of predisposing pathology or active involvement of either the mitral or aortic valve. Complicated RIE comprised patients who were not intravenous drug users, had a positive blood culture for MRSA, serum creatinine ≥2.5 mg/dL, or evidence of extrapulmonary sites of infection. Patients who were intravenous drug users, had a positive blood culture for methicillin-susceptible S. aureus (MSSA), had serum creatinine <2.5 mg/dL, and were without evidence of extrapulmonary sites of infection were considered to have uncomplicated RIE.

The coprimary efficacy endpoints in the trial were the Adjudication Committee success rates at the Test of Cure visit (6 weeks after the last treatment dose) in the ITT and Per Protocol (PP) populations. The overall Adjudication Committee success rates in the ITT population were 44.2% (53/120) in patients treated with daptomycin and 41.7% (48/115) in patients treated with comparator (difference = 2.4% [95% CI −10.2, 15.1]). The success rates in the PP population were 54.4% (43/79) in patients treated with daptomycin and 53.3% (32/60) in patients treated with comparator (difference = 1.1% [95% CI −15.6, 17.8]).

Adjudication Committee success rates are shown in Table 17.

Eighteen (18/120) patients in the daptomycin arm and 19/116 patients in the comparator arm died during the trial. These comprise 3/28 daptomycin-treated patients and 8/26 comparator-treated patients with endocarditis, as well as 15/92 daptomycin-treated patients and 11/90 comparator-treated patients with bacteremia. Among patients with persisting or relapsing S. aureus infections, 8/19 daptomycin-treated patients and 7/11 comparator-treated patients died.

Overall, there was no difference in time to clearance of S. aureus bacteremia between daptomycin and comparator. The median time to clearance in patients with MSSA was 4 days and in patients with MRSA was 8 days.

Failure of treatment due to persisting or relapsing S. aureus infections was assessed by the Adjudication Committee in 19/120 (16%) daptomycin-treated patients (12 with MRSA and 7 with MSSA) and 11/115 (10%) comparator-treated patients (9 with MRSA treated with vancomycin and 2 with MSSA treated with an anti-staphylococcal semi-synthetic penicillin). Among all failures, isolates from 6 daptomycin-treated patients and 1 vancomycin-treated patient developed increasing MICs (reduced susceptibility) by central laboratory testing during or following therapy. Most patients who failed due to persisting or relapsing S. aureus infection had deep-seated infection and did not receive necessary surgical intervention [see Warnings and Precautions ( 5.9)] .

Pediatric Patients (1 to 17 Years of Age) with S. aureus Bacteremia

The pediatric S. aureus bacteremia study was designed as a prospective multi-center, randomized, comparative trial to treat pediatric patients aged 1 to 17 years with bacteremia. Patients known to have endocarditis or pneumonia at baseline were excluded. Patients were enrolled in a stepwise approach into three age groups and given age-dependent doses of daptomycin once daily for up to 42 days. The different age groups and doses evaluated were as follows: Adolescents (12 to 17 years, n=14 patients) treated with daptomycin dosed at 7 mg/kg once daily, Children (7 to 11 years, n=19 patients) treated with daptomycin dosed at 9 mg/kg once daily and Children (2 to 6 years, n=22 patients) treated with daptomycin dosed at 12 mg/kg once daily. No patients 1 to <2 years of age were enrolled.

Patients were randomized 2:1 to receive daptomycin or a standard of care comparator, which included intravenous therapy with vancomycin, semi-synthetic penicillin, first generation cephalosporin or clindamycin. Patients could switch to oral therapy after clinical improvement was demonstrated (no minimum IV dosing was required).

The primary objective of this study was to assess the safety of daptomycin. The clinical outcome was determined by resolution or improvement of symptoms at test-of-cure (TOC) visit, 7 to 14 days after the last dose, which was assessed by the site level Blinded Evaluator.

Of the 82 subjects randomized in the study, 81 subjects were treated with daptomycin or comparator and included in the safety population, and 73 had a proven S. aureus bacteremia at Baseline. Of these, 51 subjects were randomized to the daptomycin group and 22 subjects were randomized to the comparator group. The mean duration of IV therapy was 12 days, with a range of 1 to 44 days. Forty-eight subjects switched to oral therapy, and the mean duration of oral therapy was 21 days. The clinical success rates determined at 7 to 14 days after last dose of therapy (IV and oral) (TOC visit) were 88% (45/51) for daptomycin and 77% (17/22) for comparator.